An organic electroluminescent element (also referred to as an organic EL element below) is configured to include a pair of electrodes, an anode and a cathode, and a light-emitting layer provided between the electrodes. When a voltage is applied across the electrodes, holes are injected from the anode, and electrons are injected from the cathode. These holes and electrons are combined in the light-emitting layer, thereby emitting light.
In addition to the light-emitting layer, certain layers may be provided between the pair of electrodes. For example, in order to improve electron injection efficiency from the cathode, an electron injection layer may be provided.
The electron injection layer is generally formed of a material that is unstable in air, such as Ba, BaO, NaF, and LiF. Then, the electron injection layer is generally formed in an environment isolated from air and, for example, formed by a vacuum deposition method in a vacuum atmosphere.
However, the vacuum deposition method and similar methods have, among various thin film forming methods, relatively complicated thin film forming processes. For this reason, for the purpose of simplifying the forming process of the electron injection layer, a method for forming the electron injection layer by an application method is under study. In order to form the electron injection layer by the application method, a material that is relatively stable in air is required to be developed. As such a material for the electron injection layer, for example, a complex material is developed, and a method for manufacturing an organic EL element is developed that forms a film of the complex material by the application method to form an electron injection layer (for example, see Patent Document 1).